Is it wrong to ask deceased loved ones to pray for us? I was visiting the cemetary where my maternal grandparents are buried and I started to ask my grandfather to please pray for some very important intentions for our family. Is this wrong?

__________________Thank you, St. Jude! Patron of hopeless and impossible cases!

I feel like unless the person is a venerable, blessed, or saint it is our job to pray for them.

I should pray for my grandparents and the souls in purgatory more often.

Yes, it is definitely our job to pray for the souls in purgatory. They most certainly can also pray for us, however, and there is nothing wrong in asking for their prayers. I ask my dad to pray for me and his grandson (whom he never met) all the time. And yes, I pray and make sacrifices for him as well.

Your request to them will have to remain conditional. Hard as it sounds, we are not sure if they are able or want to pray...
If we knew they were in heaven or at least in purgatory (which of course we hope)...
But of course there is nothing wrong with asking. The problem arises if someone asks deceased relatives to pray out of a false certainty that they are in heaven or purgatory. This false certainty causes problems many times in funerals (and especially eulogies, where they say them), because if one is so sure of the deceased being in heaven, it makes no sense to pray for them.
Thus in many funerals you don't hear anyone speak about judgment.
I hope people will pray for me and not praise me and ask for my prayers when I die.

No I think it is a wonderful thing to do as you pray for them they pray for you to the heavenly father, so asking them to pray for you is a great idea.

"Grant me, O Lord, a steady hand and watchful eye, that no one shall be hurt as I pass by. Thou gavest life, I pray no act of mine may take away or mar that gift of Thine.
Shelter those, dear Lord, who bear my company from the evils of fire and all calamity.Teach me to use my car for others need; Nor miss through love of undue speed.
The beauty of the world; that thus I may with joy and courtesy go on my way.
St. Christopher, holy patron of travelers, protect me, and lead me safely to my destiny. Amen." - prayer of Saint Christopher (my patron saint)

You can certainly ask for their prayers. You will have to remember, of course, that it may be impossible for them to do so. Therefore also pray to God and/or your favourite saint(s). And always pray for the deceased as they might need your prayers more than you need theirs.

__________________“Experience teaches that the man who exercises a frequent and rigid censorship over his thoughts, words and actions, is better capable of hating and avoiding evil and of cultivating earnestly what is good”
- St Pius X